User's Manual Part 1
Release8PlanningGuide
Issue2,November2007 Draft5forRegulatoryReview 134
RECOMMENDATION:
Where regulations require that radar sensing and radio shutdown is enabled, you
can most effectively share the spectrum with satellite services if you perform
spectrum analysis and select channels that are distributed evenly across the
frequency band range.
A connectorized 5.7-GHz module provides an Antenna Gain parameter. When you
indicate the gain of your antenna in this field, the algorithm calculates the appropriate
sensitivity to radar signals, and this reduces the occurrence of false positives (wherever
the antenna gain is less than the maximum).
12.3 USINGJITTERTOCHECKRECEIVEDSIGNALQUALITY(CYCLONE
FSKONLY)
The General Status tab in the Home page of the Canopy SM and BHS displays current
values for Jitter, which is essentially a measure of interference. Interpret the jitter value
as indicated in
Table 29.
Table 29: Signal quality levels indicated by jitter
Signal
Modulation
Correlation of Highest Seen
Jitter to Signal Quality
High
Quality
Questionable
Quality
Poor
Quality
1X operation
(2-level FSK)
0 to 4 5 to 14 15
2X operation
(4-level FSK)
0 to 9 10 to 14 15
In your lab, an SM whose jitter value is constant at 14 may have an incoming packet
efficiency of 100%. However, a deployed SM whose jitter value is 14 is likely to have
even higher jitter values as interfering signals fluctuate in strength over time. So, do not
consider 14 to be acceptable. Avoiding a jitter value of 15 should be the highest priority in
establishing a link. At 15, jitter causes fragments to be dropped and link efficiency to
suffer.
Cyclone modules calculate jitter based on both interference and the modulation scheme.
For this reason, values on the low end of the jitter range that are significantly higher in 2X
operation can still be indications of a high quality signal. For example, where the amount
of interference remains constant, an SM with a jitter value of 3 in 1X operation can
display a jitter value of 7 when enabled for 2X operation.
However, on the high end of the jitter range, do not consider the higher values in 2X
operation to be acceptable. This is because 2X operation is much more susceptible to
problems from interference than is 1X. For example, where the amount of interference
remains constant, an SM with a jitter value of 6 in 1X operation can display a jitter value
of 14 when enabled for 2X operation. As indicated in Table 29, these values are
unacceptable.
Cyclone OFDM uses a different modulation scheme and does not display a jitter value.